Selective Elimination of Soilborne Plant Pathogens and Enhancement of Antagonists by Steaming, Sublethal Fumigation and Soil Solarization

Abstract

Soilborne plant pathogens constitute a real menace to world agriculture due to their ability to form long-lived, dormant resting structures able to resist adverse environmental conditions even for several years but capable of resuming activity rapidly when favourable conditions return to normalcy. Soil disinfestation when applicable is almost the sole solution in controlling a wide range of them. Soil fumigation in particular drastically affects survival of soilborne plant pathogens but may concomitantly induce biological vacuum with certain serious disadvantages. Alternative solution to the problem could be the application of sublethal fumigation mostly in combination with non-chemical methods such as soil solarization (Katan, 1981). Soil solarization applied singly or in combination with reduced doses of soil fumigants showed a remarkable destructive effect on most soilborne plant pathogens. In addition to the thermal death, the debilitation of the fungal propagules induced by sublethal heating constitutes another interesting characteristic of the technique. In contrary to soil fumigation or steaming, recent data clearly demonstrate survival, increase and prevalence of heat tolerant fungal antagonists in solarized soils. This review refers to the current disinfestation methods (steaming, sublethal fumigation and soil solarization) with special emphasis on their effect on the ecology and survival of soilborne pathogens and their potential natural antagonists and the consequent effect in controlling soilborne plant diseases.